class_docstr: A null context manager for local training.
  
  Example usage:
  
  ```python
  with NullContextManager():
    model = ...
  ```
code: def __enter__(self):
      pass
  
file_path: ranking/tensorflow_ranking/python/keras/strategy_utils.py
imports: import os
  from typing import Any, Optional, Union
  import tensorflow
label_desc: Use image node_id 1 for calling the NullContextManager obj's underlying member method code with example usage: obj.__enter__() without return types